EP4389397A1 - Method and device for producing a wall of an object - Google Patents

Abstract

A method for producing at least one wall (8) of a 3-dimensional object by means of an additive manufacturing process, in which at least one manufacturing material in a flowable state is introduced into a support material from at least one introduction opening (4) of an introduction needle (2) and then hardens, wherein the wall extends along a wall profile and has a first side surface and an opposite second side surface, wherein the introduction needle is moved along a pressure path through the support material, wherein the pressure path (12) corresponds to a profile path (10) along the wall profile, on which a texturing path is superimposed.

Description

The invention relates to a method for producing at least one wall of a 3-dimensional object by means of an additive manufacturing method, in which at least one production material in a flowable state is introduced into a support material from at least one introduction opening of an introduction needle and then cured, wherein the wall extends along a wall profile and has a first side surface and an opposite second side surface, wherein the introduction needle is moved along a pressure path through the support material. The invention also relates to a method for creating a pressure path for such a method.

Additive manufacturing processes are now known in many forms from the state of the art and are used to produce very different 3-dimensional objects. Traditionally, additive manufacturing processes are hardly suitable for producing large quantities of the respective objects, as the production of individual objects takes a lot of time. In additive manufacturing processes, especially in 3D printing, the object to be produced is built up from a large number of very thin layers arranged on top of each other, which are often only a few micrometers thick. The production of large objects in particular is therefore very time-consuming.

In recent years, great progress has been made in this field. For example, MIT has developed a 3-dimensional printing process that is US 2018/281295 A1 Such a process is called "Rapid Liquid Printing" (RLP) process. The material to be produced is Object is produced in a container that contains a gel suspension or another material as a support material that does not react chemically with the production material. It serves exclusively to support the production material as long as it has not yet sufficiently hardened. In the sense of the present invention, "hardening" is also understood to mean cross-linking or another process by which the flowable production material changes to a non-flowable state. In the method, the production material in the flowable state, for example liquid or counter-shaped, is introduced into the support material at the desired position. For this purpose, at least one introduction needle is used, which has at least one introduction opening.

Such RLP processes are now used to print prosthetic liners, for example, which are worn as an intermediate layer between an amputation stump and a prosthetic shaft on which other prosthetic elements are arranged. The prosthetic liner is worn directly on the skin, so the feel is of great importance for the wearing comfort. The side facing the skin must therefore be specially designed in order to achieve the most comfortable wearing comfort for the wearer of the prosthetic liner and the prosthesis arranged above it. The same applies, however, to the opposite side facing away from the skin, as this is the side that can be touched and handled when the liner is worn. In addition, the design of this outside of the liner is a design and therefore a recognition feature.

A liner has an open proximal end into which the amputation stump is inserted. It also has a closed distal end, on which in some embodiments there is a fastening element with which a mechanical connection can be made between the distal end of the liner and a prosthetic shaft. However, such a fastening element is not necessary for all embodiments. There are therefore also liners that do not have such a fastening element. In this case, the necessary hold between the liner pulled over the amputation stump and the prosthetic shaft is often achieved by creating a negative pressure between the liner and the prosthetic shaft. The direction that extends from the distal end to the proximal end or vice versa is called the longitudinal direction of the liner.

The liner has a wall, which in this case forms the wall of the 3-dimensional object. The first side surface and the second side surface are then formed by the inside and the outside of the liner, with the inside of the liner being the side that comes into contact with the wearer's skin when worn. The outside of the liner is the side opposite the inside. Whether the inside forms the first side surface or the second side surface is irrelevant to the function of the present invention. The only important thing is that the outside forms the other side surface.

The wall of the liner extends along a wall profile. This corresponds to the cross-sectional contour of the liner. Many standard liners have a circular cross-section, with the diameter of this circle increasing from the distal end to the proximal end. In this case, the wall extends along this circle so that it forms the wall profile. However, the wall profile does not have to be circular. It can also be oval, ellipsoidal or freely designed. It can also be designed differently at different points along the longitudinal direction of the liner. In an additive manufacturing process, such as the RLP process, the production material is introduced into the support material through at least one introduction opening of the introduction needle. The amount of production material that is introduced is dosed and adjusted to the speed at which the introduction needle moves along the pressure path so that the width of the introduced strand of production material corresponds to the width of the wall. The pressure path therefore corresponds to the wall profile.

The disadvantage is that neither the first side surface nor the second side surface of the wall, which is produced by the RLP process, can be provided with a structure or texturing. EN 10 2020 118 034 A1 A device is known which can be used to carry out an RLP procedure, whereby the insertion needle used in the area of the insertion opening has a Tool with which at least one side surface of the wall to be produced can be machined. However, this usually involves smoothing the respective side surface and/or improving adhesion between a current layer of the production material being introduced and a previously introduced layer.

The invention is therefore based on the object of further developing a method in such a way that the disadvantages of the prior art are overcome or at least mitigated.

The invention solves the problem by a method according to the preamble of claim 1, which is characterized in that the pressure path corresponds to a path along the wall path, on which a texturing path is superimposed. Unlike in the prior art, the insertion needle is therefore not only moved along the path through the support material that corresponds to the wall path. Rather, a texturing path is superimposed. This means that the direction in which the at least one insertion needle is moved along the pressure path is not always identical to the direction of the wall path. The texturing path can therefore also be viewed as a deviation of the pressure path from the path, i.e. from the wall path. The texturing path can only affect one or more sections of the pressure path, so that along the other sections the pressure path corresponds to the path. Preferably, however, the texturing path does not affect just one or more sections, but the entire pressure path.

The path advantageously extends in the middle between the first side surface and the second side surface. In an additive manufacturing process such as an RLP process, the wall to be produced is produced in several layers. The strand of production material emerging from the at least one introduction opening and introduced into the support material is thus arranged in several layers on top of each other. With each layer, the wall to be produced therefore grows by the diameter of this layer. If the 3-dimensional object is, for example, a prosthetic liner, the path runs spirally from the distal end of the prosthesis liner to the open proximal end. With each layer, in this example with each turn of the spiral of the spiral-shaped path, not only does the wall grow, but also its first side surface and the opposite second side surface. The path preferably runs in the middle between the position of the two side surfaces of the wall at the point on the wall that is to be produced by the respective layer. This can, but does not have to, be the middle of the previous layer. In particular, if the wall has an incline because, for example, the circumference of an object to be manufactured, such as a liner, changes, in particular increases in size, the path for the current layer of the strand of production material to be introduced is not in the middle of the previous layer, but is offset from this middle.

The path is preferably spiral-shaped. The wall to be produced particularly preferably has a closed cross-section, which is, for example, circular, oval, ellipsoidal or free-form. It can preferably be parameterized by parameters such as a radius, a diameter and/or a radius of curvature.

The texturing path preferably contains at least one oscillation or consists of at least one such oscillation. The oscillation is preferably a sinusoidal oscillation, a triangular oscillation or a rectangular oscillation. The oscillation can preferably be parameterized by a wavelength and an amplitude. If the texturing path has at least one oscillation, this means that the printing path deviates alternately on both sides from the course path. The insertion needle therefore deviates alternately to the left and right in the direction of movement of the insertion needle along the printing path, from the course path and thus from the actual wall course. A triangular oscillation or a rectangular oscillation is characterized by the geometric shape of this deviation. In a triangular oscillation, the insertion needle initially moves linearly in one direction away from the course path, then describes a tight curve, which is also known as a kink. or corner, and then moves linearly back towards the path. In a square wave, the insertion needle first moves away from the path at a right angle, then moves parallel to the path for a predetermined distance, and then moves back towards the path at a right angle.

By using at least one oscillation in the design of the texturing path, the first side surface and/or the second side surface of the wall to be produced can be provided with texturing. The oscillation has a wavelength and an amplitude. Interesting effects can be achieved in particular with a spiral design of the path in which the path runs in turns. The wavelength can be designed in such a way that it fits into the length of a turn as an integer. In this case, the pressure path deviates identically from the path in successive turns. The deviations occur radially outwards or radially inwards. At the points where the pressure path deviates radially outwards in one turn, it also deviates radially outwards in the following turn. The same applies to a deviation radially inwards. There is therefore no phase shift of the oscillation of the texturing path from one turn to the following turn.

This is different if the wavelength of the oscillation is not designed in such a way that it fits into the length of the winding as an integer. Phase shifts then occur in successive windings, which can result in different effects and designs of the texture and structure on the first side surface and/or the second side surface of the walls to be produced.

Preferably, the wavelength is larger than a diameter of the insertion opening of the insertion needle through which the stiffening material is introduced into the support material and/or larger than the wall thickness of the wall. Preferably, the wavelength is more than three times, particularly preferably more than four times as large. This is in contrast to FDM printing (FDM: Fused Deposition Modelling, This is a process known as fusion layering (German: Schmelzschichtung), in which a high wall thickness is created by guiding a printing needle along a printing path that has the tightest possible serpentine lines. This makes it possible to produce a wall thickness that is significantly greater than the opening of the printing needle. A structure on one side surface of the wall produced in this way is to be avoided, which is why the tightest possible serpentine lines are used.

Preferably, the wavelength and/or the amplitude of at least one oscillation of the texturing path varies over the course of the texturing path. If the wavelength is varied over the course of the texturing path, this results in the structure or texture produced on the first side surface and/or the second side surface changing and the above-mentioned phase shift also varying in the case of a spiral-shaped course of the printing path. If the amplitude is varied over the course of the texturing path, this results in the depth of the structure or texture produced in the first side surface and/or the second side surface varying.

Preferably, the texturing path has a superposition of several oscillations or consists of such a superposition. Each of the oscillations superimposed in this way can be a sinusoidal oscillation, a triangular oscillation or a rectangular oscillation. Of course, other types of oscillation are also possible. The individual oscillations that are superimposed for the texturing path advantageously have different wavelengths and/or different amplitudes.

In a preferred embodiment, the amplitude of at least one oscillation, preferably all oscillations, of the texturing path corresponds to a maximum of the wall thickness, preferably a maximum of 75% of the wall thickness, preferably a maximum of 50%, particularly preferably a maximum of 15% of the wall thickness. The choice of a larger amplitude is particularly useful, but not only, when a larger wall thickness is to be achieved, i.e. the wall of the object is to be thickened in a spatially limited area.

• Bereitstellen von Objektdaten eines 3-dimensionalen Objektes, die Informationen über den Wandungsverlauf einer Wandung des Objektes enthalten,
• Bereitstellen von Texturierungsinformationen, die Informationen über eine gewünschte Texturierung der ersten Seitenfläche und/oder der zweiten Seitenfläche der Wandung enthalten,
• Ermitteln eines Verlaufspfades aus den Objektdaten und eines Texturierungspfades aus den Texturierungsinformationen,
• Erstellen des Druckpfades durch überlagern des Verlaufspfades mit dem Texturierungspfad.

The invention also solves the problem by a method for creating a print path for a method described here, which is characterized by the following steps:

• Providing object data of a 3-dimensional object containing information about the wall profile of a wall of the object,
• Providing texturing information containing information about a desired texturing of the first side surface and/or the second side surface of the wall,
• Determining a gradient path from the object data and a texturing path from the texturing information,
• Create the print path by overlaying the gradient path with the texturing path.

The course path is determined from the macroscopic shape and geometry of the 3-dimensional object to be produced. A texture or structure that is to be present in the first side surface or the side surface has no influence here. The texturing information is analyzed for the texturing path. It contains information about the desired structure or texture of the first side surface and/or the second side surface. However, this information alone is usually not sufficient to create a texturing path. Instead, the object data is usually also used for this purpose, since the texturing path to be used also depends on the geometry and shape of the wall to be produced.

Preferably, only the texturing information and information about the size of the first side surface and/or the second side surface are used to determine the texturing path. Particularly preferably, a Fourier transformation of the texturing information, in particular of the desired texture and structure, which is suitably parameterized, is carried out to determine a texturing path. In this way, the structure and texture can be converted into a Superposition of oscillations, preferably sinusoidal oscillations, which can then be used as a texturing path.

Preferably, the desired texturing contains a logo and/or lettering.

The at least one insertion needle through which the production material is introduced into the support material has at least one insertion opening through which the production material exits. This insertion opening is generally directed backwards in the direction of movement of the insertion needle. In a preferred embodiment, however, this insertion opening points in a direction that encloses an angle other than 0° and 180° with the direction of movement of the insertion needle. The insertion opening particularly preferably points in a direction that encloses an angle of 90° with the direction of movement of the insertion needle. To achieve this, a particularly preferred embodiment uses an unrolled or curved insertion needle. In this way, a surface structuring can be achieved that is only pronounced on one side surface of the wall and is present in a weaker form or not at all on the opposite side surface. This side surface, which is little or not at all structured, is preferably the side facing the insertion needle. When inserting a layer of the production material, the insertion needle preferably smoothes the previously inserted underlying layer, whereby the respective side surface is formed entirely without or with only a smaller structure than the side surface of the wall facing away from the insertion needle.

Preferably, the wall is constructed from layers of the production material arranged next to one another, wherein there is a phase shift of an oscillation of the texturing path between adjacent layers, which is preferably between 160° and 200°.

In a specific embodiment, a prosthetic liner is manufactured using the additive manufacturing process, which has a closed distal end, a open proximal end and a longitudinal direction that extends from the distal end to the proximal end. In an area between the distal end and the proximal end, the wall of the prosthesis liner is created by the insertion needle describing a spiral-shaped pressure path. In this way, the liner is built up layer by layer, starting from the distal end. From a predetermined height, i.e. a predetermined distance from the distal end along the longitudinal direction of the liner, the pressure path is formed from a path that corresponds to the spiral and a texturing path. For example, a sinusoidal oscillation with an amplitude of 0.2 mm is selected for the texturing path. In the example described, the wall thickness of the walls to be produced is 2 mm, the layer spacing, i.e. the offset of the spiral after one revolution, is 0.5 mm, for example. The wavelength of the sinusoidal oscillation is chosen so that it does not fit into the circumference of the spiral and thus of the liner to be produced as an integer. In this embodiment, 11.53 wavelengths fit into one circumference. This creates a phase shift of around 190.8°. If the wavelength were chosen to be slightly larger, so that exactly 11.5 wavelengths fit into one circumference of the liner, this would result in a phase shift of 180°. It has proven advantageous to vary the wavelength. In a specific embodiment, a wavelength of U/11.53 is chosen for a predetermined number of revolutions of the spiral, where U is the length of the circumference of the spiral. For example, 32 revolutions of the spiral are printed using this wavelength. Then a different wavelength, for example U/11.47, is selected and kept constant for a further 32 revolutions of the spiral. In this way, arrow-like structures can be produced on the outside, i.e. on a side wall of the prosthetic liner.

• Figur 1 - die schematische Darstellung eines additiven Fertigungsverfahrens
• Figur 2-3 - schematische Darstellungen von Verlaufspfad und Texturierungspfad,
• Figur 4-5 - die schematische Darstellung unterschiedlicher 3-dimensionaler Objekte und
• Figur 6a-6c - schematische Darstellungen unterschiedlicher Druckpfade.

Some embodiments of the present invention are explained in more detail below with the help of the accompanying drawings. They show

• Figure 1 - the schematic representation of an additive manufacturing process
• Figure 2-3 - schematic representations of gradient path and texturing path,
• Figure 4-5 - the schematic representation of different 3-dimensional objects and
• Figure 6a-6c - schematic representations of different printing paths.

Figure 1 shows schematically the functionality of an RLP process. An insertion needle 2 is guided along a pressure path, the Figure 1 not shown separately, is moved by a support material that is also not shown. In the Figure 1 In the embodiment shown, there is an insertion opening 4 at the lower end of the insertion needle 2 through which the production material 6 emerges. It can be seen that this is applied in layers on top of each other and thus forms a wall 8. This wall 8 has Figure 1 does not have a structure or texture on one of the side surfaces. The pressure path along which the insertion needle 2 is moved through the support material coincides with the course of the wall 8 and therefore consists of only one course path.

Figure 2 shows such a course path 10, which is shown as a dotted line. The course of this course path 10 corresponds to the course of the wall 8 to be produced. A texturing path is superimposed on the course path 10, which is a sinusoidal oscillation in the embodiment shown. The superimposition of the course path 10 with the texturing path produces the printing path 12, which is shown as a solid line. It can be seen that the printing path 12 deviates alternately to the left and right from the course path 10. The maximum distance between the printing path 12 and the course path 10 corresponds to the amplitude of the sinusoidal oscillation that forms the texturing path. The distance between adjacent interfaces between the printing path 12 and the course path 10 corresponds to half the wavelength of the sinusoidal oscillation that forms the texturing path.

As in Figure 1 As shown, the wall 8 is usually constructed from several layers of the production material 6. If, for example, a prosthesis liner is manufactured, the path corresponds to a spiral path. After each revolution, a layer of the production material is applied to an already existing layer of the production material. This situation is in Figure 3 The dotted line shows the path 10. A section of the print path 12 is also shown as in Figure 2 In addition, a further section 14 of the pressure path 12 is shown, which corresponds to the pressure path 12 during a later revolution. The two sections of the pressure path 12 therefore correspond to the positions at which production material is introduced from the insertion needle 2 during successive revolutions of the pressure path. It can be seen that there is a phase shift of almost 180° between the two sections of the pressure path.

Figure 4 shows a prosthetic liner 16, the base body of which was produced using an RLP process. A structured area 18 can be seen, which was produced using a process according to an embodiment of the present invention. The sinusoidal oscillation superimposed on the path 10 leads, as shown in the Figures 2 and 3 can be seen, to a structure on the side surfaces of the manufactured wall. This is shown by the line pattern 20. Each individual line corresponds to a belly of the sinusoidal oscillation, which leads to an outwardly protruding curvature in the wall. Between two adjacent curvatures a receding curvature is created. The phase shift results in the image shown. In the lower area, the nodes of the sinusoidal curve used as a texturing path shift from one layer to the adjacent layer to the right. Depending on the direction of the printing path, this means that the phase shift between two adjacent layers, as in Figure 3 shown, is slightly larger or slightly smaller than 180°. In the upper area of the line pattern 20, the structure turns around. The nodes of the sine curve used as a texturing path shift to the left from layer to layer. The phase shift between adjacent layers is now slightly smaller or slightly larger than 180° depending on the direction of the print path. In this way, different structures can be introduced into the side surfaces of the objects to be manufactured. Figure 5 shows three printed objects where a sine curve was used as the texturing path, the amplitude of which increases from object to object from right to left.

Figure 6a shows a top view of a printing path 12, which is designed as a spiral printing path 12. Two layers are shown, which are arranged one on top of the other in a direction perpendicular to the plane of the drawing. It can be seen that the texturing path is a sine curve, with adjacent layers have a phase shift of about 180°. In Figure 6b further revolutions of this pressure path 12 are shown. It can be seen here that the phase shift is not exactly 180°. If one assumes that the pressure path is traversed clockwise, the phase shift is slightly larger than 180°. In Figure 6c the printing path is shown with even more revolutions. On the one hand, you can see that the radius of the wall to be produced and thus the radius of the path increases. In addition, after a predetermined number of revolutions, the wavelength of the sine curve used as the texturing path has changed, so that the phase shift is now slightly less than 180°.

List of reference symbols

• 2 insertion needle
• 4 Insertion opening
• 6 Manufacturing material
• 8 Wall
• 10 History path
• 12 Texturing path
• 14 Section
• 16 liners
• 18 structured area
• 20 line patterns

Claims (9)

Method for producing at least one wall of a 3-dimensional object by means of an additive manufacturing process, in which at least one production material in a flowable state is introduced into a support material from at least one introduction opening of an introduction needle and then hardens, wherein the wall extends along a wall profile and has a first side surface and an opposite second side surface, wherein the introduction needle is moved along a pressure path through the support material,
characterized in that the printing path corresponds to a path along the wall profile, on which a texturing path is superimposed. Method according to claim 1, characterized in that the progression path extends in the middle between the first side surface and the second side surface. Method according to claim 1 or 2, characterized in that the texturing path includes an oscillation, preferably a sinusoidal oscillation, a triangular oscillation or a rectangular oscillation, or consists of such an oscillation which has a wavelength and an amplitude. Method according to claim 3, characterized in that the wavelength and/or the amplitude varies over the course of the texturing path. Method according to claim 3 or 4, characterized in that the texturing path includes a superposition of several oscillations. Method according to one of claims 3 to 5, characterized in that the amplitude corresponds maximally to the wall thickness, preferably maximally to 75% of the Wall thickness, particularly preferably a maximum of 50% of the wall thickness of the wall. Method for creating a print path for a method according to one of the preceding claims, characterized by the following steps: - Providing object data of a 3-dimensional object containing information about the wall profile of a wall of the object, - Providing texturing information containing information about a desired texturing of the first side surface and/or the second side surface of the wall, - Determining a gradient path using the object data and a texturing path using the texturing information, - Create the print path by overlaying the gradient path with the texturing path. Method according to claim 7, characterized in that the desired texturing contains a logo and/or lettering. Method according to one of claims 3 to 8, characterized in that the wall is constructed from layers of the production material arranged next to one another and there is a phase shift of an oscillation of the texturing path between adjacent layers, which is preferably between 160° and 200°.

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